The truth about soapstone
In many areas of heating technology, false promises are made in advertising. This happens partly out of ignorance or deliberately. We leave what is worse to you.
Often references are made to the “naturalness” of soapstone. It is a mystery to us what should be more “natural” about soapstone than chamotte, which is made of fired clay and has been used in stove construction for thousands of years. Soapstone has also hit the headlines because it is suspected of being carcinogenic.
When promoting soapstone, some key figures are not interpreted correctly. The main difference between soapstone and conventional fireclay material is the higher density of the soapstone. The density of soapstone is 2.7 to 2.8 g / cm³, that of fireclay is 2.0 g / cm³. The specific storage capacity of both materials is 0.28 Wh / kgK (amount of heat per kg and per Kelvin temperature difference). This means that 1 kg of soapstone has the same heat storage capacity as 1 kg of chamotte.
For example, one manufacturer claims that a mixture of approx. 80% chamotte and approx. 20% soapstone can increase the storage capacity by 30% (from 0.28 to 0.364 Wh / kgK). To achieve this, the added soapstone would have to have a storage capacity of 0.70 Wh / kgK, as shown by the following simple equation.
80% * 0.28 Wh / kgK + 20% * 0.70 Wh / kgK = 0.364 Wh / kgK
Due to the same specific storage capacity of both materials, this is simply physical nonsense, which is even claimed in a utility model. (Document number for DPMA on request)
In a report available to us from the TU Bergakademie Freiberg from July 22, 2004, a heat storage device (according to advertising "Stone of the Wise") from this manufacturer was investigated, but chemical and mineral analyzes did not reveal any corresponding content of MgO or the minerals soapstone or the phases arising therefrom become.
Such aggressive advertising statements that are incorrect in terms of content are intended to suggest that the products are of higher value than competitors. Inferior quality should be disguised, such as the smaller surfaces of the radiators or unsightly plastic cladding. Finally, however, the enormous purchase price must be justified, which is often up to 300% higher than that of the competition.